4 throttles' Vacuum Corolla Levin AE101 4A-GE 20v

[Rinconrolla]

This is a Quad Throttle Bodies (4 throttles) from Toyota Corolla Levin / Trueno AE101. It is also some times refer to as ITB (Individual Throttle Bodies).



1. Brake vacuum from side of throttle 1 behind butterfly (big hole)

2. Fuel return to tank (entry) [from regulator]

3. Fuel return to tank (exit) [to fuel tank]

4. Brake vacuum from side of throttle 4 behind butterfly (big hole)

5. Idle Speed Control Valve (ISCV entry)

The brake vacuum is taken from throttle 1 & 4 via a side port. They are summed by a T-joint before connected to the brake servo. Since throttle 4 is far from brake servo hence it is connected to another pipe then to the T-joint (not shown).





1. Brake vacuum

2. Fuel input

3. ISCV input

4. Pressurized output for air-cond idle up valve

5. Pressurized output for power steering idle up valve at steering rack & pinio

6. From point 11 (hidden behind point 3) pressurized

7. From point 10 vacuum of throttle 4 - going to Throttle Opener

8. To Charcoal Filter

9. Fuel return to tank (exit) [to fuel tank]

10. vacuum to point (suspect to point 7



In order to get very stabilized "balanced" vacuum, drill extra hole pointed by the circle below for optimum performance



Individual throttle body vacuum matching / balancing via mechanical fine tuning through valve opening. The valve limits the amount of air that by-pass the butterfly.

There are two holes behind the butterfly.



Idle Speed Control Valve - output then finally into intake via the red circle below



Notice the old 4 throttles (shown below) does not have the opening (shown above) and that the injectors output spray is significantly hindered when comparing 4 throttles from generation year 91 against year 93 June till 20vMAP edition. The year 93 unit is so much better.

But this does not mean the old 4 throttle does not have all 4 ISCV holes. They are hidden from current view, but shown by the 4 purple arrows




1. Brake vacuum from side of throttle 1 behind butterfly (big hole)

2. Fuel return to tank (entry) [from regulator]

3. Fuel return to tank (exit) [to fuel tank]

4. Brake vacuum from side of throttle 4 behind butterfly (big hole)

5. Idle Speed Control Valve (ISCV entry)

Red color

1. ISCV
2. ISCV
3. ISCV
4. ISCV

ISCV holes from 1st generation ITB.

[trife96]

Jan 31, 2011 22:11:10 GMT -5 Rinconrolla said:

This is a Quad Throttle Bodies (4 throttles) from Toyota Corolla Levin / Trueno AE101. It is also some times refer to as ITB (Individual Throttle Bodies).






5. Pressurized output for power steering idle up valve at steering rack & pinio

I'm confused cause this port is input, not output. I have a strong vacuum on port #5 and was trying to figure out where it went

[sk149]

Here you go hope this helps mine just has a block off

[trife96]

That's what I was planning on doing and just adjust the throttle linkage cause when unplugged, the RPM is way up over 2000rpm and when i plug it off, it drops to almost as low as 500rpm which is a bit to low for idle. Should be around 750rpm. I'm assuming it went to the stock air box, but haven't really look at it yet. But thanks for the input